Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Qual é a média mensal de emissões de gases de efeito estufa nos últimos 12 meses?
 ###Tabelas: 
CREATE TABLE emissions (emission_id INT, emission_date DATE, amount_emitted FLOAT); INSERT INTO emissions (emission_id, emission_date, amount_emitted) VALUES (1, '2022-01-01', 12000), (2, '2022-01-02', 11000), (3, '2022-01-03', 13000), (4, '2022-02-01', 10500), (5, '2022-02-02', 11500), (6, '2022-02-03', 10000), (7, '2022-03-01', 9500), (8, '2022-03-02', 10000), (9, '2022-03-03', 9000);
SELECT AVG(amount_emitted) as avg_emission FROM emissions WHERE EXTRACT(MONTH FROM emission_date) IN (EXTRACT(MONTH FROM CURRENT_DATE)-11, EXTRACT(MONTH FROM CURRENT_DATE)-10, EXTRACT(MONTH FROM CURRENT_DATE)-9, EXTRACT(MONTH FROM CURRENT_DATE)-8, EXTRACT(MONTH FROM CURRENT_DATE)-7, EXTRACT(MONTH FROM CURRENT_DATE)-6, EXTRACT(MONTH FROM CURRENT_DATE)-5, EXTRACT(MONTH FROM CURRENT_DATE)-4, EXTRACT(MONTH FROM CURRENT_DATE)-3, EXTRACT(MONTH FROM CURRENT_DATE)-2, EXTRACT(MONTH FROM CURRENT_DATE)-1, EXTRACT(MONTH FROM CURRENT_DATE)) AND EXTRACT(YEAR FROM emission_date) = EXTRACT(YEAR FROM CURRENT_DATE);